def calCircleArea(r):
    s=3.14*r*r
    print("圆面积为%0.2f"%s)
    return s

def calRectArea(a,b):
    s1=a*b
    print("长方形的面积为%0.2f"%s1)

num=int(input())

result=calCircleArea(num)
print("园的面积为：%0.2f"%result)
